DNA Structure and Replication

This set of flashcards covers key vocabulary related to DNA structure and replication, including definitions of important concepts and terminology.

Chargaff's Rule

States that in DNA, the amount of adenine (A) equals thymine (T), and the amount of cytosine (C) equals guanine (G).

Antiparallel Strands

Refers to the opposite directional orientation of the two strands in a DNA double helix; one strand runs 5’ to 3’ while the complementary strand runs 3’ to 5’.

Phosphodiester Bond

A covalent bond formed between the 3’ hydroxyl group of one nucleotide and the 5’ phosphate group of another nucleotide in the sugar-phosphate backbone of DNA.

PCR (Polymerase Chain Reaction)

A laboratory technique used to amplify specific DNA sequences by repeated cycles of heating and cooling.

Helicase

An enzyme that unwinds the DNA double helix during replication.

DNA Polymerase III

An enzyme responsible for synthesizing new DNA strands by adding nucleotides to a growing chain during DNA replication.

Okazaki Fragments

Short, newly synthesized DNA fragments formed on the lagging strand during DNA replication.

Messelson and Stahl Experiment

An experiment that provided evidence for the semi-conservative model of DNA replication by distinguishing old and new strands of DNA.

Melting Temperature (Tm)

The temperature at which half of the DNA strands are in the double helix state and half are in the 'melted' single-stranded state; influenced by the GC content.

5’ End of DNA

The end of a DNA strand where a phosphate group is attached, indicating the directionality of the strand.

3’ End of DNA

The end of a DNA strand that has a hydroxyl (-OH) group, marking the other directionality of the strand.

Base Pairing

The specific pairing of nitrogenous bases in DNA, where adenine pairs with thymine and cytosine pairs with guanine.